1. Field of the Invention
The present invention relates to a circuit board and a chip package structure, in particular, to a circuit board having a pad of a non-solder mask defined configuration and a chip package structure.
2. Description of Related Art
The flip chip bonding technology disposes a plurality of chip pads on an active surface of a chip mainly in an area array manner and forms a plurality of bumps on the chip pads respectively. Next, the chip is flipped so that the bumps on the chip are electrically and mechanically connected to a plurality of pads on a chip carrier respectively.
The configuration of the pad on the chip carrier can be generally classified into two categories, that is, solder mask defined (SMD) and non-solder mask defined (NSMD) according to whether the solder mask covers the pad or not. Herein, NSMD is also referred to as pad defined. To the NSMD pad, as the opening of the solder mask layer exposes the pad entirely, the pad cannot be fixed on the substrate of the chip carrier via the solder mask layer and is easy to be peeled off.